The present invention relates to a composting plant for composting organic material such as household waste separated at the source, organic sludge from waste water treatment plants and industries, wood chippings, straw and farmyard manure, as well as to a method for composting such waste.
The simplest way of dealing with organic waste is to simply store the waste at a refuse dump. However which, however, this may entail serious environmental problems such as pollution of the ground water, gas emission, leachate, odour, contamination, dissemination, etc. Alternatively the organic waste can be composted by being fragmented, mixed and deposited in a pit or stack. In order to achieve the optimum conditions such as supply of the necessary quantity of oxygen, the waste is aerated from time to time by shifting the stacks. The composted waste can be used as a means of soil amelioration. Both cases are energy consuming.
The waste may otherwise be disposed of by incineration, by which a certain energy output can be recovered. This, however, entails a need for flue gas purification and disposal of the ashes. Furthermore, the initial costs are rather exorbitant. Organic, waste can also be treated in biogas plants, during which inflammable gases are generated. The degassed material can be used as organic fertilizer. The object is to provide a simple, reliable and effective composting plant having low establishing and operating costs and having a high degree of stabilizing of the composted waste which upon completion of the process can be utilized as a growth substance described as quality compost.
From SE-A 366 289 a composting plant is known where the compost material is advanced by means of a row of spirals and where the aeration takes place through the spiral shafts.
From U.S. Pat. No. 410,348 discloses is known a plant where the compost material is placed in a pit and is turned from time to time by a special turnover machine. From DE-C 36 37 393 is mown a plant where the compost material is aerated from ace bottom. In none of these cases is the generated heat energy utilized. From DE-A 42 08 390 is known a system for removal of odorants in the exhaust fumes from a composting plant.
The object of the invention is to provide a composting plant with an active usage of the heat energy generated at the putrefactive process, at the same time achieving a high quality of the finished composted material and without the plant causing any odour nuisance.